

A081357


Sublime numbers, numbers for which the number of divisors and the sum of the divisors are both perfect.


3




OFFSET

1,1


COMMENTS

a(2) was calculated by K. S. Brown.


REFERENCES

J.M. De Koninck, Those Fascinating Numbers, Amer. Math. Soc., 2009.
M. J. Halm, More Sequences, Mpossibilities 83, April 2003
C. A. Pickover, Wonders of Numbers, p. 215


LINKS

Table of n, a(n) for n=1..2.
K. S. Brown, Odd Sublime Numbers (posting to sci.math newsgroup)
K. S. Brown, Sublime Numbers
J. Griffiths, Lopsided numbers, Mathematical Spectrum, 43 (No. 2, 2010/2011), 5354.
Dean Hickerson, Re: Twelve is special (posting to sci.math newsgroup)
C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Zentralblatt review
GĂ©rard Villemin, Nombre sublime (French)


EXAMPLE

a(1) = 12 because 12 + 6 + 4 + 3 + 2 + 1 = 28 is perfect and number of divisors, 6, is also perfect.


CROSSREFS

Sequence in context: A175906 A144546 A165970 * A127708 A094896 A277118
Adjacent sequences: A081354 A081355 A081356 * A081358 A081359 A081360


KEYWORD

hard,nonn,bref,more


AUTHOR

Michael Joseph Halm, Apr 20 2003


STATUS

approved



